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铝合金选区激光熔化成形过程中热力耦合分析及残余应力预测

Thermal coupling analysis and residual stress prediction of aluminum alloy SLM

  • 摘要: 本文利用ANSYS有限元分析软件对AlSi10Mg的选区激光熔化成形过程进行热–力耦合分析并进行实验验证。针对目前铝合金选区激光熔化数值模拟不够精确,残余应力预测效率低的问题,利用JMatPro软件计算出AlSi10Mg在不同温度下的非线性热物性参数,并通过ANSYS的UDMAT子程序实现材料状态的转换,以此提高数值模拟的准确度。通过建立的热力耦合数值模型,研究不同的激光工艺参数对温度场和应力场的影响,最后进行相应的AlSi10Mg样件打印实验,并通过X射线应力分析仪测量样件残余应力。结果表明:每一层的扫描过程中,曲线均有明显的波峰,轨道间和层间可实现较好的重熔搭接;随着扫描速率的减小或激光功率的增加,最高温度和熔池尺寸随之增加;在成形过程中,沿着扫描方向的应力最大,垂直于扫描方向的应力最小。通过热力耦合模型所得到的残余应力与实验值误差小于8%,可以通过该热力耦合模型对选区激光熔化制件的残余应力进行预测。

     

    Abstract: In this paper, the thermal and mechanical coupling analysis of AlSi10Mg SLM forming process is carried out by using ANSYS finite element analysis software and experimental verification is carried out. Aiming at the problem that SLM numerical simulation of aluminum alloy is not accurate enough and the residual stress prediction efficiency is low, JMatPro software is used to calculate the nonlinear thermal physical property parameters of AlSi10Mg at different temperatures, and the material state transformation is realized by UDMAT subroutine of ANSYS, so as to improve the accuracy of numerical simulation. The influence of different laser process parameters on temperature field and stress field was studied through the thermodynamic coupling numerical model established. Finally, the corresponding AlSi10Mg sample printing experiment was carried out, and the residual stress of the sample was measured by X-ray stress analyzer. The results show that there are obvious peaks in the curves during the scanning of each layer, and good remelting lap between tracks and layers can be achieved. With the decrease of scanning rate or the increase of laser power, the maximum temperature and molten pool size increase. In the forming process, the stress along the scanning direction is the largest, and the stress perpendicular to the scanning direction is the smallest. The error between the residual stress and the experimental value obtained by the thermodynamic coupling model is less than 8%. The residual stress of SLM can be predicted by the thermodynamic coupling model.

     

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